(A parallel discussion, on the politics and diplomacy, is going on here: https://www.physicsforums.com/showthread.php?t=145129) "A Rare Material and a Surprising Weapon" (NYT) So then - who had the means to do this? Is there any possibility of rogue organizations having stolen large quantities of this radioisotope, to "discredit" Putin's administration (as he claims)? (last paragraph in article) Or are the nuclear superpowers the only possible assassins here? Are the quantities used in ionization sources (LANL periodic table, under "uses") of the order of magnitude to be usable? What about radioisotope thermal generators - are there any recent ones with Po-210, and could it have been stolen from there? And any speculation as to why such a crazy, exotic assassination, one that's so obvious and incriminating?